O’Neill said the player was likely undergoing his medical at that very moment and admitted he was naturally disappointed to lose him after all he had contributed.
He noted it was difficult to change the player’s mind. Without this opportunity, he felt the player would have been content to stay. Even when Nottingham Forest made a late approach in January, the player didn’t complain.
O’Neill accepted it was a big chance for the player and a tough one to turn down.
He understood Engels’ urgency to complete the move, especially after Canada right-back Alistair Johnston—who had interest from Everton—suffered a leg muscle injury.
Ideally, O’Neill would have preferred the player to remain and finish the next two matches, said the 74-year-old, who is back at work following a medical procedure last week.
He accepted that was unlikely. With Johnston having played while an offer was on the table and then getting injured—potentially jeopardising any move—there was understandable concern.
O’Neill suggested Arne likely feared a similar scenario and said he could see it from a player’s perspective.
Johnston was withdrawn at half-time in Celtic’s 5-1 victory over Kilmarnock on Sunday.
O’Neill said Johnston would be sidelined for a few weeks and would be past the transfer deadline by the time he returned, praising the defender’s stoic response.
He called it a shame but stressed the issue is not long-term and that Johnston will be back.
Celtic have added Egypt winger Haissem Hassan and Germany Under-21 midfielder Mika Baur this week, and O’Neill expects more signings to follow.
One possible arrival is Chelsea left-back Landon Emenalo on loan as cover for Kieran Tierney, after the 18-year-old toured the Lennoxtown training centre this week.
O’Neill described Emenalo as a very promising young player and said the position needs depth. He praised Tierney’s superb season after injury troubles at Arsenal and noted the youngster’s current minor injury should clear soon.
If that happens, O’Neill said he would be keen to bring him in.